Centrifuge (100lb capacity; 200G)

Model # of equipment:

Custom-built

Brief Description of equipment:

In the field of geotechnical engineering, the centrifuge modeling technique has secured its place in the art of laboratory testing. This technique has been applied to a wide variety of topics such as slope stability, performance of footings and piles, seepage flow, and solute transport. Because full-scale field testing of highway facilities is expensive and time-consuming, pavement researchers have been seeking a laboratory simulation method that can aid in predicting the field performance and failure modes of prototype structures. Centrifuge modeling has emerged as one promising laboratory technique for predicting the response of highway structures.

Features
ORITE has a large centrifuge, capable of holding up to 100 lbs (45.5 kg) at an arm length of 4.46 ft. (1.36 m). The centrifuge can produce a maximum acceleration of 200 times normal gravity (G). This enables ORITE to determine, for example, the effect of large forces on performance of pipe and bridge models. These tests are much faster and far less expensive than measurements on actual structures. The centrifuge can also be used to study the flow of liquids through porous materials. Tests conducted thus far indicate that this procedure is a viable alternative to in-situ testing.

Capabilities of the equipment:

ApplicationsCentrifuge modeling involves utilization of a high-intensity gravitational acceleration in the centrifuge environment. There are two main steps in this method:

A model of the prototype is made with a uniform scaling factor of 1/n.

The model is subjected to a centrifugally-created artificial gravity field of n times the normal gravitational field.

By applying the scaling relations, various parameters defining performance of the model are transformed to those of the prototype.

As an example of the application of the centrifuge, realistic modeling of the behavior of underground pipe by even the most sophisticated numerical methods, can be limited because of the complex nature of the pipe–soil interaction and because of the nonuniform and nonlinear properties of soil. A scaled-down corrugated high-density polyethylene (HDPE) pipe, installed in granular backfill under a shallow cover, was tested in the ORITE centrifuge environment. Results on the model pipe were compared with the response of a prototype 37-inch-diameter (0.94 m) corrugated HDPE pipe installed and tested at the ORITE outdoor load frame. The results demonstrated that centrifuge modeling is a promising technique for predicting deflection response of buried HDPE pipes. Similar modeling has been conducted on spread footings for bridges.